WO2011148866A1

WO2011148866A1 - Battery

Info

Publication number: WO2011148866A1
Application number: PCT/JP2011/061614
Authority: WO
Inventors: 佐々木　丈
Original assignee: 株式会社Ｇｓユアサ
Priority date: 2010-05-26
Filing date: 2011-05-20
Publication date: 2011-12-01
Also published as: US8956748B2; US20130071712A1; JP5737289B2; CN102893439B; JPWO2011148866A1; CN102893439A

Abstract

Disclosed is a battery that makes a positive electrode plate and negative electrode plate of a power-generating element of a battery function as effectively as possible. The battery comprises a power-generating element that is formed on a plane, wherein a foil positive electrode plate (23a) and a foil negative electrode plate (23b), each having an active material layer, wind around a core (21) with separators (24a, 24b) sandwiched therebetween. The core (21) is formed by a porous material, and in the circumference of the innermost winding, the foil positive electrode plate (23a) and the foil negative electrode plate (23b) are positioned facing each other, with the surfaces that form the active material layers thereof sandwiching the core (21).

Description

battery

The present invention relates to a power generation in which a foil-like positive electrode plate and a foil-like negative electrode plate each having an active material layer formed thereon are wound around a core with a separator between them and formed into a flat shape. The present invention relates to a battery having an element.

The power generation element that constitutes such a battery is a power generation element of a type called a so-called wound battery element, and is formed in a flat shape in particular because of a demand for thinning.

The basic configuration of such a power generation element is formed by winding a foil-like positive electrode plate and a foil-like negative electrode plate each having an active material layer formed around a core with a separator interposed therebetween. As a method for forming a flat shape, for example, Patent Document 1 below discloses a method of forming the core itself into a flat shape. Further, there is a forming method such as winding a foil-like positive electrode plate or the like around a cylindrical core having a substantially circular cross section and then pressing and crushing it from the side.

By reducing the thickness of the power generation element to a flat shape as described above, not only heat dissipation is improved, but also when using a rectangular battery case, a dead space between the power generation element and the inner surface of the case There is an advantage that the power generation element can be arranged by effectively utilizing the volume in the housing.

Japanese Patent Laid-Open No. 11-339839

However, in the above-described conventional configuration, usually, at the position where the negative electrode plate or the positive electrode plate in the power generation element starts rolling, one electrode plate (usually, the negative electrode plate) is wound so as to make one round around the winding core. Therefore, in the innermost circumference of the winding, the negative electrode plates (or the positive electrode plates) face each other, and there is an electrode plate portion that does not function as a battery.

In the case where the negative electrode plates face each other at the innermost circumference of the winding, the innermost negative electrode plate wastes ions (lithium ions in the case of a lithium ion battery) to reduce the capacity retention rate of the battery. End up. Even when the innermost periphery is a positive electrode plate, the active material of the positive electrode plate does not function effectively.

The present invention has been made in view of such circumstances, and an object thereof is to make the positive electrode plate and the negative electrode plate of the power generation element function as effectively as possible.

In order to achieve this object, the first characteristic configuration of the battery according to the present invention is that a foil-like positive electrode plate and a foil-like negative electrode plate each having an active material layer formed are wound with a separator interposed therebetween. A foil-shaped positive electrode plate that is wound around a core and has a power generation element formed in a flat shape, wherein the core is composed of a porous member, and an active material layer is formed on each of the cores And the foil-like negative electrode plate are arranged so as to face each other with the winding core in between at the innermost circumference of the winding.

Thus, in the innermost circumference where the foil-shaped positive electrode plate or the foil-shaped negative electrode plate starts to be wound on the winding core, which is the core material for winding in the wound power generation element, the foil-shaped positive electrode plate and the foil-shaped negative electrode plate are Since the core that is opposite and located between the two is composed of a porous member, the substance that constitutes the reaction process of the battery such as ions moves between the two and the discharge reaction or accurately Charge / discharge reaction proceeds.
That is, the foil-like positive electrode plate and the foil-like negative electrode plate function as a battery even at the innermost periphery of the power generation element.

Here, the porous member refers to a member having a large number of fine through movement paths through which substances constituting a reaction process such as ions can move between the foil-like positive electrode plate and the foil-like negative electrode plate facing each other. In other words, it includes those formed by a foaming technique and those formed by a fused nonwoven fabric.

Further, in order to dispose the surfaces of the active material layer formed on each of the foil-like positive electrode plate and the foil-like negative electrode plate so as to face each other with the winding core sandwiched between the innermost circumferences of the winding, It is possible to employ a configuration in which the starting positions of the rolled positive electrode plate and the foil negative electrode plate on the winding core are displaced by a half circumference. Further, various aspects such as attaching a porous sheet member having a length corresponding to a half circumference of the core as a lead to one end of the foil-like positive electrode plate or the foil-like negative electrode plate, so that both of them are rolled out from the same position, etc. Can be realized.

In the second characteristic configuration, in addition to the first characteristic configuration, the power generation element is configured such that the sheet-like member having flexibility is formed in a cylindrical shape, and the foil-shaped positive electrode is formed on the winding core. After the plate and the foil-like negative electrode plate are wound with the separator sandwiched therebetween, they are formed in a flat shape by pressing in the normal direction of the outer peripheral surface.

That is, since the core for winding the foil-like positive electrode plate or the like is formed of a sheet-like member, the core can be easily configured as a porous member.

In the third characteristic configuration, in addition to the first or second characteristic configuration, the power generation element is provided on the winding surface of the foil-shaped positive plate, the foil-shaped negative plate or the separator in the core. A positioning member for positioning the foil-like positive electrode plate or the foil-like negative electrode plate in contact with the tip of the foil-like positive electrode plate or the foil-like negative electrode plate is attached.

That is, when the surface of the active material layer formed on each of the foil-like positive electrode plate and the foil-like negative electrode plate is disposed so as to face each other with the core in the innermost circumference of the winding, It is desired that the positive electrode side and the negative electrode side are appropriately opposed with a large area as much as possible. For this reason, by providing the positioning member, the starting position is set accurately.

In the fourth feature configuration, in addition to the third feature configuration, the positioning member has one end fixed to the winding surface of the winding core, the foil-like positive electrode plate, the foil-like plate. It exists in the point comprised by the sheet-like member extended along the winding direction of a negative electrode plate or the said separator.

According to the above configuration, the winding start position is accurately determined by applying the tip of the foil-like positive electrode plate or the foil-like negative electrode plate to the base end position of the sheet-like positioning member fixed to the winding surface of the winding core. In this state, if the foil-like positive electrode plate or the foil-like negative electrode plate and the sheet-like positioning member are rolled together, it can be easily wound.

The fifth characteristic configuration is that, in addition to the fourth characteristic configuration, the positioning member is configured by fixing a leading end portion of the separator on the winding start side to the core.

That is, the separator is also used as the positioning member by fixing the tip of the separator to the core by, for example, fusion.

In the sixth feature configuration, in addition to any of the third to fifth feature configurations, the positioning member positions the foil-like positive electrode plate and the foil-like negative electrode plate. Are provided in a pair in a state of being distributed to both ends in the longitudinal direction of the winding core as viewed in the winding axis direction.

That is, by shifting the starting position of the foil-shaped positive electrode plate and the foil-shaped negative electrode plate relative to the winding core, the surfaces of the foil-shaped positive electrode plate and the foil-shaped negative electrode plate on which the active material is formed are opposed to each other with the core interposed therebetween. It becomes a state to do. At this time, the foil-like positive electrode plate and the foil-like negative electrode plate can be appropriately opposed to each other in the innermost periphery of the power generation element.

The seventh characteristic configuration is that, in addition to any of the first to sixth characteristic configurations, the core and the separator are formed of separate members.

Since the core and the separator are composed of separate members, the characteristics such as support characteristics and shape retention for each electrode piece required as the core, and the characteristics such as insulation and flexibility required as the separator Thus, it is possible to appropriately ensure the use of individual materials suitable for each of them, and to fully exhibit the expected performance as a power generation element.

The eighth characteristic configuration is that, in addition to the seventh characteristic configuration, the winding core incorporated in the power generation element has a flat cylindrical shape.

In the ninth feature configuration, in addition to the eighth feature configuration, the width on the short width side of the core in the direction of the winding axis of the foil-like positive electrode plate and the foil-like negative electrode plate is 1 mm. It is the point which is 10 mm or less.

The tenth characteristic configuration is that, in addition to the seventh characteristic configuration, the winding core is set to have higher rigidity than the separator.

According to the above characteristic configuration, both electrode pieces and the separator are wound and formed in a flat shape, so that sufficient support characteristics and shape retention can be ensured for both the electrode pieces and the separator. .

The eleventh characteristic configuration is that, in addition to any one of the first to ninth characteristic configurations, the size of the hole of the porous core is 1 μm or more and 1000 μm or less.

According to the first characteristic configuration, the foil-like positive electrode plate and the foil-like negative electrode plate function as a battery even at the innermost periphery of the power generation element, so that the positive electrode plate and the negative electrode plate of the power generation element function as effectively as possible. It was to get.

In addition, according to the second characteristic configuration, the winding core when winding the foil-like positive electrode plate or the like is formed of a sheet-like member, so that the winding core can be easily configured as a porous member. Can contribute to the reduction of the manufacturing cost of the battery.

In addition, according to the third feature configuration, the foil-shaped positive electrode plate and the foil-shaped negative electrode plate function efficiently as a battery in the innermost circumference by providing the positioning member and accurately setting the starting position. Can be made.

Further, according to the fourth characteristic configuration, the foil-like positive electrode plate or the foil-like negative electrode plate, with the tip of the foil-like positive electrode plate or the foil-like negative electrode plate applied to the base end position of the sheet-like positioning member, Since the foil-like positive electrode plate or the foil-like negative electrode plate can be positioned simply by rolling together with the sheet-like positioning member, the positioning operation of the foil-like positive electrode plate or the foil-like negative electrode plate can be easily performed. it can.

Moreover, according to the fifth characteristic configuration, since the separator can be used as the positioning member, it is possible to contribute to the reduction of the manufacturing cost of the battery.

Further, according to the sixth feature configuration, the foil-like positive electrode plate and the foil-like negative electrode plate can be properly opposed to each other in the innermost periphery of the power generation element. Can effectively function as a battery.

FIG. 1 is an external perspective view of a battery according to an embodiment of the present invention. FIG. 2 is a perspective view showing the internal structure of the battery according to the embodiment of the present invention. FIG. 3 is a front view showing the internal structure of the battery according to the embodiment of the present invention. FIG. 4 is a schematic diagram showing the configuration of the power generation element according to the embodiment of the present invention. FIG. 5 is a perspective view of the core according to the embodiment of the present invention. FIG. 6 is an explanatory diagram of the manufacturing process of the power generation element according to the embodiment of the present invention. FIG. 7 is a schematic diagram showing a configuration of a power generation element according to another embodiment of the present invention. FIG. 8 is an explanatory diagram of the manufacturing process of the power generating element according to another embodiment of the present invention.

Hereinafter, embodiments of the battery of the present invention will be described with reference to the drawings.
In the present embodiment, a non-aqueous electrolyte secondary battery (more specifically, a lithium ion battery) which is an example of a secondary battery will be described as an example.

[Configuration of Nonaqueous Electrolyte Secondary Battery RB]
1 and 2 are perspective views of the nonaqueous electrolyte secondary battery RB of the present embodiment, and FIG. 3 is a front view thereof. The non-aqueous electrolyte secondary battery RB includes a casing having a substantially flat lid portion 2 that is welded to the open surface of a bottomed cylindrical (more specifically, a bottomed rectangular cylindrical) can body 1. Has the body BC.

The lid 2 is formed in a rectangular shape, and the casing BC has a flat rectangular parallelepiped shape as a whole. FIG. 2 is a perspective view in which the can body 1 is removed from the secondary battery RB that is the completed product shown in FIG. 1, and shows the configuration inside the casing BC. Further, FIG. 3 shows the can body 1 by a two-dot chain line and seeing through the inside of the casing BC.

Inside the housing BC, a power generation element 3 and current collectors 4 and 6 indicated by a two-dot chain line in FIGS. 2 and 3 are housed and arranged so as to be immersed in the electrolytic solution. As will be described in detail later, the power generation element 3 has an active material applied to each of a pair of electrode plates composed of a foil-like positive electrode plate and a foil-like negative electrode plate, and a separator is sandwiched between them. It has been turned.

In the power generation element 3, the active material uncoated portion of the foil-shaped positive electrode plate is laterally extended and welded to the current collector 4, and the active material uncoated portion of the foil-shaped negative electrode plate is disposed on the opposite side. It is extended and welded to the current collector 6.

The lid 2 made of metal (specifically, made of aluminum) has a current collector 4 on the positive electrode side, a terminal bolt 5 which is a positive electrode terminal connected to the current collector 4, and a negative electrode side current collector 4. A current collector 6 and a negative terminal bolt 7 connected to the current collector 6 are attached.

The terminal bolt 5 is fixedly attached to the lid portion 2 by sandwiching a pair of

packings

9 and 10 arranged with the lid portion 2 sandwiched between the head of the terminal bolt 5 and the current collector 4. This is done by caulking the rivet 5a formed on the head.

The negative electrode side has the same structure, and a pair of

packings

11, 12 arranged with the lid 2 sandwiched between them are sandwiched between the head of the terminal bolt 7 and the current collector 6, and placed on the head of the terminal bolt 7. The terminal bolt 7 is fixed to the lid by caulking the formed rivet 7a (see FIG. 3).

The electrode structure on the negative electrode side including the

terminal bolts

5 and 7 and the current collectors 4 and 6 and the electrode structure on the positive electrode side are in a symmetrical arrangement, and only the material of the metal member is different. The metal member on the positive electrode side is made of aluminum, and the metal member on the negative electrode side is made of copper.

[Manufacturing process of secondary battery RB]
Next, the manufacturing process of the secondary battery RB will be schematically described.
First, assembly of the power generation element 3 will be described.
The power generating element 3 includes a foil-like positive electrode plate and a foil-like negative electrode plate formed by applying a positive electrode active material and a negative electrode active material to the front and back surfaces of a long strip of aluminum foil and copper foil, respectively, and forming an active material layer therebetween. It is manufactured by winding it around a core 21 shown in FIG.

The core 21 is made of a material that is an electrically insulating material and can withstand an electrolytic solution. Specifically, a resin such as PPS (polyphenylene sulfide), PP (polypropylene), PE (polyethylene) and PVDF (polyvinylidene fluoride) may be used, but PPS is preferable from the viewpoint of heat resistance.

The core 21 is formed in a cylindrical shape by rolling a flexible rectangular porous sheet-like member. The core 21 has an electrolyte and lithium constituting a charge / discharge reaction process. A fine through path that allows a substance such as ions to pass therethrough is formed.

The effective diameter of this through path (through hole) is about the same as the particle size of the active material of the foil-shaped positive electrode plate or foil-shaped negative electrode plate (average of about 10 μm), and is 1 μm to 1000 μm. The range is preferable, and the range of 1 μm to 100 μm is particularly preferable. The winding core 21 is formed so that there are innumerable such fine holes so that the active material is exposed to the electrolytic solution as much as possible through the through path.

Further, as will be described in detail later, since the foil-shaped positive electrode plate and the foil-shaped negative electrode plate face each other with the winding core 21 in between in the process of producing the power generation element, The thickness of the sheet-like core 21 is set so that electrical insulation between the two is maintained even when the core 21 is in close contact with the core 21.

As shown in FIG. 5, strip-shaped

positioning members

22a and 22b are arranged on the outer peripheral surface of the cylindrical core 21 (the wound surface of the foil-like positive electrode plate 23a and the like), and one end on the long side is the core 21. Are arranged in a symmetric posture with respect to the central axis of the core 21 while being fixedly held on the outer peripheral surface of the core 21.

Therefore, the

positioning members

22a and 22b are arranged so as to extend from one end side fixed to the outer peripheral surface of the core 21 along the winding direction of the foil-like positive electrode plate 23a and the like.

Of the pair of

positioning members

22a and 22b, one positioning member 22a is bonded and fixed in a state in which the tip is slightly protruded when a cylindrical core 21 is formed by rolling a sheet-like member. To form.

The other positioning member 22b is formed by cutting a sheet-like member made of the same material as the core 21 into a strip shape, and fixing one end of the long side thereof to the outer peripheral surface of the core 21.

FIG. 6 shows a schematic winding process of the foil-like positive electrode plate 23a, the foil-like negative electrode plate 23b, and the

separators

24a and 24b around the winding core 21 having the above shape.

Separator

24a, 24b can be comprised using the microporous film and nonwoven fabric of polyolefin type, polyester type, polyacrylonitrile type, polyphenylene sulfide type, polyimide type, a fluororesin type, for example.

In the figure, the winding roller 25 is passed through the hollow portion of the winding core 21, and a foil shape is interposed between the winding roller 25 and a pressure-bonding roller 26 that is pressure-bonded to the outer peripheral surface of the winding roller 25. A state is schematically shown in which the negative electrode plate 23b and the separator 24b are fed and wound.

In the present embodiment, the starting positions of the foil-shaped positive electrode plate 23a and the foil-shaped negative electrode plate 23b are shifted along the circumferential direction of the core 21, and the respective starting positions of the winding are positioned on the

positioning members

22a and 22b. It stipulates. That is, in the present embodiment, the starting positions of the foil-like positive electrode plate 23 a and the foil-like negative electrode plate 23 b are shifted by a half circumference of the core 21.

The foil-like positive electrode plate 23a or the foil-like negative electrode plate 23b may be started in advance, but in the present embodiment, the case of starting to foil from the foil-like negative electrode plate 23b is illustrated and schematically described.

In a state where the winding core 21 is set on the winding roller 25, the rotational position of the winding core 21 is set so that the position of the positioning member 22b is positioned before the pressing position by the pressing roller 26 (state shown in FIG. 6). .

From this state, the foil-like negative electrode plate 23b and the separator 24b are firmly inserted between the positioning member 22b and the outer peripheral surface of the core 21 with their tips aligned and positioned. At this time, the separators 24b are overlapped so that the separators 24b are located on the outer peripheral side of the foil-like negative electrode plate 23b.

Although schematically shown in FIG. 6, the width of the separator 24 b is substantially the same as the height of the core 21, whereas the width of the foil-like negative electrode plate 23 b is wider than the height of the core 21. 6 protrudes from the range where the core 21 is present to the near side in FIG. This protruding portion is an uncoated portion 3a to which no active material is applied, and this uncoated portion 3a is connected to the current collector 6 in a later step.

After inserting the foil-like negative electrode plate 23b or the like into the position of the positioning member 22b, the winding roller 25 is rotationally driven in the direction indicated by the arrow in FIG. 6, and the positioning member 22a on the opposite side is positioned at the position of the positioning member 22b in FIG. The foil-like positive electrode plate 23a and the separator 24a are firmly inserted between the positioning member 22a and the outer peripheral surface of the core 21 with their tips aligned, and positioned. Also here, the separators 24a are overlapped so that they are positioned on the outer peripheral side of the foil-like positive electrode plate 23a.

Although not shown, the foil-like positive electrode plate 23a is also wider than the height of the core 21, and the foil-like positive electrode plate 23a is uncoated on the opposite side (the back side in FIG. 6) from the foil-like negative electrode plate 23b. The engineering part 3a protrudes, and the protruding part is connected to the current collector 4 in a later process.

The foil-like negative electrode plate 23b and the separator 24b inserted between the positioning member 22b and the outer peripheral surface of the winding core 21 pass through the pressure-bonding position of the pressure-bonding roller 26, and then the rotation axis of the winding roller 25. Until one round is made around, the leading end side maintains the posture along the outer peripheral surface of the core 21 only by the holding force sandwiched between the positioning member 22b and the outer peripheral surface of the core 21. In this case, since the sheet-like members constituting the

positioning members

22a and 22b are formed in a relatively strong sheet, the tips of the foil-like negative electrode plate 23b and the separator 24b can be reliably held.

If the tips of the foil-like negative electrode plate 23b and the separator 24b cannot be reliably held between the positioning member 22b and the outer peripheral surface of the core 21, the length of the positioning member 22b on the side that begins to roll in advance (the length of the core 21) (Length in the circumferential direction) is formed to be slightly longer than one circumference of the outer periphery of the core 21, so that the tips of the foil-like negative electrode plate 23 b and the separator 24 b are maintained along the outer peripheral surface of the core 21. You can do that.

Thereafter, the foil-like positive electrode plate 23a, the separator 24a, the foil-like negative electrode plate 23b, and the separator 24b are sequentially stacked on the core 21 from the inner peripheral side.

After winding the foil-shaped positive electrode plate 23a and the like of a predetermined length, the foil-shaped positive electrode plate 23a is removed from the winding roller 25, pressed in the normal direction of the outer peripheral surface, and formed into a flat shape, thereby forming the flat power generation element 3. . In other words, the core 21 is a functional component that is disposed at the winding center and that constitutes the power generation element 3 for maintaining the shape of the power generation element 3 and that is disposed in the battery even after the battery is manufactured. is there.

In FIG. 4, a state in which the foil-like positive electrode plate 23 a and the like are wound around the winding core 21 in a state where the power generating element 3 is in a flat shape is schematically shown in the winding axis direction view of the winding core 21. Yes. In this state, the winding core 21 incorporated in the power generation element 3 has a flat cylindrical shape.

As shown in FIG. 4, the attachment base end positions of the pair of

positioning members

22a and 22b are positioned so as to be distributed to the both ends in the longitudinal direction of the flat shape when viewed from the winding axis direction of the foil-like positive electrode plate 23a or the like. In addition, the power generation element 3 is crushed.

Therefore, in the innermost circumference of the winding, the foil-like positive electrode plate 23a and the foil-like negative electrode plate 23b face each other with the active material layer formed on both sides of the winding core 21, and on the opposite surfaces. The formed active material layer functions effectively as a battery.

4, the width of the flat core 21 (width on the short width side) is 1 mm or more and 10 mm or less at least at the end in the longitudinal direction, as viewed in the winding axis direction indicated by the symbol A in FIG. The material and thickness of the winding core 21 and further the conditions for pressing when the foil-like positive electrode plate 23a and the like wound around the winding core 21 are crushed are set.

This is because when the width A is too narrow, the foil-like negative electrode plate 23b or the like existing along the outer peripheral surface of the narrow portion is bent at a sharp angle rather than a curved shape, This is because the conductivity may be deteriorated and the

adjacent separators

24a and 24b may be damaged. In order to avoid such a situation, the size of the width A is set as described above. ing.

That is, when the width on the short width side of the winding core 21 is set to 1 mm or more when viewed in the winding axis direction, the possibility that the innermost electrode plate is bent and damaged is reduced. Moreover, the fall of the volume efficiency as a battery can be suppressed by making the width | variety by the side of a short width into 10 mm or less.

Further, since the core 21 has a material and a thickness so as to be more rigid than the

separators

24 a and 24 b, the support characteristics for the foil-

like electrode plates

23 a and 23 b required as the core 21. It is possible to appropriately ensure characteristics such as shape retention and characteristics such as insulation and flexibility required for the separator by using individual materials suitable for each.

As a result, the power generation element 3 can sufficiently exhibit its expected performance without causing an inconvenient situation in which the foil-like negative electrode plate 23b or the like is bent at a sharp angle. Further, it is preferable that the winding core 21 has a higher bending elastic modulus, a higher bending strength, or a stronger waist than the

separators

24a and 24b.

Next, the assembly of the lid part 2 will be described.
The lid portion 2 has the current collectors 4 and 6 and the

terminal bolts

5 and 7 sandwiched between the

packings

9, 10, 11, and 12 on an aluminum plate material in which electrode mounting holes for attaching the

terminal bolts

5 and 7 are formed. In this state, the rivets 5a and 7a are caulked and fixed.

Next, the uncoated portion 3a of the power generation element 3 is welded and connected to the current collectors 4 and 6 fixed to the lid portion 2 as described above, so that the lid portion 2 and the power generation element 3 are integrated. Turn into.

Furthermore, the assembly of the casing BC of the secondary battery RB is completed by housing the power generation element 3 in the can 1 and welding the lid 2 and the can 1.

When the assembly of the case BC is completed, an electrolyte is then injected into the case BC from an injection port (not shown). When the injection of the electrolyte is completed, the initial charge of the secondary battery RB is performed under predetermined charging conditions. The secondary battery RB is completed by performing (preliminary charging) and further performing aging and the like.

[Another embodiment]
Hereinafter, other embodiments of the present invention will be listed.

(1) In the above embodiment, the case where the

positioning members

22a and 22b are formed of the same material as that of the core 21 composed of a sheet-like member is exemplified. Can also be configured.
For example, the

separators

24a and 24b themselves may be used as positioning members.

Specifically, as shown in FIG. 8 corresponding to FIG. 6, separators 24 a, instead of the

positioning members

22 a, 22 b are attached to the mounting positions of the

positioning members

22 a, 22 b on the outer peripheral surface of the core 21 in the above embodiment. The tip of 24b is fixed by fusion or the like.

Then, as shown in FIG. 8, the foil-like negative electrode plate 23b is inserted between the separator 24b and the outer peripheral surface of the core 21 so as to be applied to the attachment base end position of the separator 24b, and the winding roller 25 is inserted. In FIG. 8, the foil-like negative electrode plate 23b is wound together with the separator 24b by being driven to rotate in the direction indicated by the arrow.

Thereafter, when the attachment base end position of the separator 24a is moved to the position of the separator 24b in FIG. 8, the separator 24a is placed between the separator 24a and the outer peripheral surface of the core 21 so as to be applied to the attachment base end position. In the state where the foil-like positive electrode plate 23a, the separator 24a, the foil-like negative electrode plate 23b and the separator 24b are superposed in order from the inner peripheral side, the wire is wound around the winding core 21 by the rotational driving of the winding roller 25.

The positions of the uncoated portions 3a of the foil-like positive electrode plate 23a and the foil-like negative electrode plate 23b are the same as in the above embodiment.
The subsequent processing is the same as in the above embodiment, and after winding the foil-like positive electrode plate 23a and the like on the winding core 21, it is removed from the winding roller 25 and pressed in the normal direction of the outer peripheral surface to be crushed. The power generation element 3 has a flat shape.

FIG. 7 schematically shows a state in which the foil-like positive electrode plate 23 a and the like are wound around the core 21 in a flat shape, as viewed from the central axis direction of the core 21.
As shown in FIG. 7, the attachment base end positions of the

separators

24a and 24b functioning as a pair of positioning members are distributed to both ends of the flat shape in the longitudinal direction as viewed in the winding axis direction of the foil-like positive electrode plate 23a and the like. The foil-like positive electrode plate 23a and the foil-like negative electrode plate 23b are opposed to each other with the core 21 sandwiched between them on the innermost circumference of the winding. The active material layer that functions effectively functions as a battery.

Furthermore, the width (short width side width) of the flat winding core 21 as indicated by the symbol A in FIG. 7 when viewed in the winding axis direction is at least 1 mm or more at the end in the longitudinal direction. The material and thickness of the winding core 21, and further, the conditions for pressing when crushing the rolled positive electrode plate 23a or the like around the winding core 21 are set as in the above embodiment. It is.

(2) In the above embodiment, the sheet-like member is rolled into a cylindrical shape to form the winding core 21, and the winding core 21 has a hollow shape. For example, the corner portion in contact with the foil-like negative electrode plate 23b is rounded. You may form in the flat solid rectangular parallelepiped shape which gave.

Even in the case of forming in this way, the winding core is made of an electrically insulating material and porous as in the above-described embodiment so as to allow permeation of the electrolytic solution and the like. What is necessary is just to comprise so that the foil-like negative electrode plate 23b may be begun to be wound from one of the longitudinal ends of the winding core, and the foil-like negative electrode plate 23b be begun to be wound from the other end.

(3) In the above embodiment, the positive electrode active material layer in the region facing the front surface and the back surface of the end portion (also referred to as the front end) of the foil-shaped negative electrode plate of the foil-shaped positive electrode plate. However, the positive electrode active material layer may not be present in the region. By adopting this configuration, it is possible to prevent the formation of lithium metal dendrite at the tip of the foil-like negative electrode plate.

This effect is exhibited as long as the positive electrode active material layer in the region does not contribute to the charge / discharge reaction, so that the surface of the positive electrode active material layer is made of lithium ions or the like instead of having no positive electrode active material layer. It is good also as a structure covered with the layer which consists of a material with a small substance permeability or zero.

The state in which the positive electrode active material layer does not exist can be achieved by peeling the positive electrode active material layer, or the active material is applied using a so-called intermittent coating method in which the active material is not previously applied to the corresponding portion. Can also be achieved. The latter method is preferable compared to the former method in that the peeling step can be omitted.

When adopting a configuration in which the active material is not present in the region facing the front and back surfaces of the tip of the foil-shaped negative electrode plate among the foil-shaped positive plates, the position of the starting end of the negative electrode is It is preferable that it is one of the both ends of a flat shape in the longitudinal direction when viewed in the axial direction. This is because, in the foil-like positive electrode plate, the region (region A) facing the front surface of the tip of the foil-like negative electrode plate and the region facing the back surface (region B) can be made continuous. This is because processing for providing a region where no active material is present on the foil-like positive electrode plate is easy.

As shown in FIG. 4, the region A and the region B are continuous when the position of the starting end portion of the negative electrode is on one of the both ends in the flat shape when viewed in the winding axis direction. On the other hand, when the position of the starting end portion of the negative electrode is in another part, the region A and the region B are arranged apart from each other. As described above, it is usually difficult to peel off the active materials in regions away from each other or to provide an uncoated portion because high positional accuracy is required.

3 Power generation element 21

Core

22a, 22b Positioning member 23a Foil-shaped positive plate 23b Foil-shaped

negative plate

24a, 24b Separator

Claims

A battery having a power generation element formed in a flat shape while being wound around a core with a foil-like positive electrode plate and a foil-like negative electrode plate each having an active material layer sandwiched between them. Because
The core is composed of a porous member,
A battery in which the foil-like positive electrode plate and the foil-like negative electrode plate, each having an active material layer formed thereon, are disposed so as to face each other with the winding core in the innermost circumference of the winding.
The power generation element has the foil-like positive electrode plate and the foil-like negative electrode plate sandwiched between the foil-like positive electrode plate and the foil-like negative electrode plate on the core formed by forming a flexible sheet-like member into a cylindrical shape. The battery according to claim 1, wherein the battery is formed into a flat shape by being pressed in a normal direction of the outer peripheral surface after being wound in a state.
The power generation element is in contact with a winding surface of the foil-like positive electrode plate, the foil-like negative electrode plate or the separator in the winding core, in contact with a tip portion of the foil-like positive electrode plate or the foil-like negative electrode plate, The battery according to claim 1 or 2, wherein a positioning member for positioning the foil-like positive electrode plate or the foil-like negative electrode plate is attached.
The positioning member is a sheet-like member that extends along the winding direction of the foil-like positive electrode plate, the foil-like negative electrode plate, or the separator with one end fixed to the winding surface of the core. The battery according to claim 3, comprising:
The battery according to claim 4, wherein the positioning member is configured by fixing a leading end portion of the separator on the winding start side to the core.
The positioning member is arranged in such a manner that a member for positioning the foil-like positive electrode plate and a member for positioning the foil-like negative electrode plate are distributed to both ends in the longitudinal direction of the core as viewed in the winding axis direction. The battery according to any one of claims 3 to 5, which is provided in a pair.
The battery according to any one of claims 1 to 6, wherein the core and the separator are made of different members.
The battery according to claim 7, wherein the core incorporated in the power generation element has a flat cylindrical shape.
9. The battery according to claim 8, wherein a width on the short width side of the winding core in the winding axis direction view of the foil-like positive electrode plate and the foil-like negative electrode plate is 1 mm or more and 10 mm or less.
The battery according to claim 7, wherein the winding core is set to have higher rigidity than the separator.
The battery according to any one of claims 1 to 9, wherein a size of the hole of the core is 1 µm or more and 1000 µm or less.